Conventionally, the electric power steering device having a motor as its source of driving power is known. For example, as disclosed in a patent document, JP 2013-153619 A (Patent document 1), an electric power steering device has a first inverter for applying a voltage to a first winding wire and a second inverter for applying a voltage to a second winding wire, and a voltage applied to the second finding wire is controlled based on a deviation of the electric currents (i.e., a difference between an electric current supplied to the first winding wire, and an electric current supplied to the second winding wire).
The controller of an alternating current rotating electric machine disclosed in the patent document 1 is applied to the electric power steering device. In the patent document 1, an electric current instruction value is calculated so that the alternating current rotating electric machine (i.e., a motor), generates an assist torque that assists a steering torque of the steering system. However, the patent document 1 is silent on how the assist torque that assists the steering torque is distributed among each of the plural systems of the winding wires.